The Hustler (ハッスルねじ巻き Hassuru neji-maki) or HotFoot It Key in the English dub, is a gadget of Doraemon. It appears on the Anime as well as on the movie Stand by Me Doraemon.
Function[]
If one put this on his/her back and wind the screw, his/her movement will be quicker and will be able to move smoothly.